Science

10:57 am

Sat November 19, 2011

Perhaps Scientists Like Lab Mice TOO Much

A technician holds a laboratory mouse at the Jackson Laboratory in Bar Harbor, Maine. The lab ships more than two million mice a year to qualified researchers.

Robert F. BukatyAP

The lab mouse is the most ubiquitous animal in biomedical research, but that doesn't mean it's always the best subject for researching disease.

In a series of articles for Slate magazine, Daniel Engber looked into why the mouse is such a mainstay of science — and whether that's a good thing.

"All of this is about standardization," Engber tells weekends on All Things Considered guest host Laura Sullivan. "It's easier for scientists — and it's cheaper — if everyone's using the same animal."

A 2008 study by the European Union found that mice accounted for about 59 percent of animals used for lab experiments. In fact, the number of mice studies has quadrupled since 1965, according to the National Library of Medicine databases. In contrast, studies on dogs and cats, rabbits, guinea pigs, zebra fish, fruit flies and other animals have remained about the same.

There's a monoculture in biomedical research that revolves around mice testing, Engber explains. Mice are easy to get and easy to maintain. It's easier to acquire grant money for studies on mice than for other, more complicated animals. But that doesn't mean they're the right animal for the job.

Take tuberculosis, for example. Mice have been used almost exclusively in tuberculosis research for the last 30 or 40 years, Engber says, but because the human respiratory system is structured differently, mice and humans actually get different types of tuberculosis.

"Any animal model you use for disease is going to be similar to the human version of disease in some ways and different in other ways," he says. "If all of your experiments are done on the same animal, those differences are just going to keep coming up again and again and again. It's self-limiting."

Not only that, lab mice are sedentary and overweight compared to their wild counterparts. Engber says that can skew the baseline of any study requiring a healthy mouse for a constant.

So why not switch to another animal?

Mice remain the number one subjects because so many tools used in research and genetic engineering are built around the mouse, Engber says. For many scientists, switching would be expensive and abrupt — almost like switching a language.

"In science, in bio-medicine, people talk about being, you know, 'I'm a mouse person. I'm a monkey person'," Engber says. "At conferences, the mouse people will sort of cluster around posters of mouse studies and monkey people will cluster around posters of monkey studies."

But with the modern lab mouse almost exhaustively studied, he suggests, diversification could lead to new scientific discoveries.

"Let's invest more money into at least developing the science of the naked mole rat, the marmoset, the python — whatever. Some other animals that might have some other secrets to share about the nature of disease."

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Transcript

LAURA SULLIVAN, HOST:

The modern lab mouse is the most ubiquitous animal in biomedical research. In the U.S. and other parts of the world, mice studies have quadrupled since 1965. One study found they make up 60 percent of animals used in experiments while studies on dogs and cats, rabbits and guinea pigs, zebra, fish and fruit flies have remained about the same. Daniel Engber, in a series of articles for Slate magazine, recently took the time to ask why - why the mouse is such a mainstay of science and whether that's a good thing.

DANIEL ENGBER: All of this is about standardization. You know, it's easier for scientists, and it's cheaper if everyone's using the same animal, and that animal is produced in factory setting. And then these animals can be distributed and people from different labs can compare their results. But really, when you look back at the history of it, we could have chosen something else. And it's just once we chose the specific kind of animal, the ball got rolling, and then there was an incentive to stay focused on that animal.

SULLIVAN: You wrote in the article that for scientists to change from mice to a different animal would be like changing their religion.

ENGBER: Yeah. I mean, in science, in biomedicine, people talk about being, you know, I'm a mouse person, oh, I'm a monkey person. At conferences, the mouse people will sort of cluster around posters of mouse studies and the monkey people will cluster around posters of monkey studies. And also, if you publish a paper - let's say you're a mouse person, you did a study using mice - it's going to be other people in your community who are the peer reviewers for that paper, who help decide whether you should get a grant to continue your mouse research. So there are these very contained groups of people and the mouse community happens to be much bigger than any of the other communities.

SULLIVAN: And this has had a lot of implications for some of the results of the studies that scientists have conducted. One of them that you mention was a series of studies on tuberculosis.

ENGBER: Right. So mice have been used almost exclusively in tuberculosis research for the last 30 or 40 years. And again, that allows a lot more experiments to be done for the same amount of money because mice are so efficient and so cheap. But there are problems, and in that particular case, mice just don't get the same kind of tuberculosis that humans get. So the question is any animal model you use for disease is going to be similar to the human version of the disease in some ways and different in other ways. If all of your experiments are done on the same animal, those differences are just going to keep coming up again and again and again. You know, it's self-limiting.

SULLIVAN: I mean, why not just switch to another animal?

ENGBER: Well, switching to another animal would be very, very expensive at this point. I mean, we've already come so far in mouse research, and we have all of these wonderful tools, genetic tools and just accumulated knowledge about the mouse. We just have to rebuild all of that knowledge and rebuild all those tools. We'd have to figure out how to do all the things, all the genetic engineering we can do with mice. We'd have to figure out how to do that with some other animal, and we're starting to learn some of those things for animals like the marmoset and even the rat.

But another idea would be to say, OK, we have all these wonderful tools for the mouse, but let's invest more money into at least developing the science of the naked mole rat, the marmoset, the python, whatever - some other animals that might have some other secrets to share about the nature of disease.

SULLIVAN: Daniel Engber is a senior editor at Slate magazine. And you can find a link to his reporting on lab mice on our website, npr.org. Daniel, thanks so much.